Doleromyrma darwiniana (Forel 1907)

Compiled by Warwick Don & Richard Harris

Biostatus: Introduced

Classification

Family:	Formicidae
Subfamily:	Dolichoderinae
Tribe:	Dolichoderini
Genus:	Doleromyrma
Species:	darwiniana

Common name(s)

Darwin's ant (Keall 1979)

Synonyms (WWW5)

Tapinoma darwinianum Forel, Iridomyrmex darwinianus (Forel)

Valid subspecies

Darwiniana fida (Forel), Darwiniana leae Forel

Origin

The genus Doleromyrma contains only a single described species and two subspecies and is endemic to Australia (Shattuck 1999). It appears to be confined there, apart from D. darwiniana, which is established in New Zealand. This species was first recorded as nesting here in 1959, from Penrose, Auckland (Taylor 1959). The nest was destroyed by Department of Agriculture officials. A probably separate establishment in Christchurch was first reported in 1979 (Keall 1979) and it has since been located at several localities in the Christchurch-Lyttelton area (Keall & Somerfield 1980).

Distribution

Apart from some spreading northward in the Auckland area, this species still tends to remain associated very closely with towns or cities with ports, strongly suggesting separate port invasions in some cases. Thus it has been recorded in Whangarei, Mt Maunganui, Gisborne, Napier, Blenheim, Nelson and Lyttelton.

General Description

Identification

Workers in the genus Doleromyrma have 12-segmented antennae. The mandibles have 4-5 teeth and 4-5 denticles. The front margin of the clypeus has downwardly curved hairs. The upper face of the propodeum is shorter than the rear face. The petiolar node is inclined forward.

Diagnostic features of the worker

Length about 2 mm; colour of head dark brown, rest of the body and legs light brown. Refer also to the generic features above. Similar in appearance to Argentine ants ( L. humile ) but workers are easily separated in the field as they give off a strong odour when crushed (cf. little or no odour for Argentine ants).

[Doleromyrma darwiniana] head. Image: April Nobile (Specimen code: CASENT0009949). www.antweb.org Image — Doleromyrma darwiniana head. Image: April Nobile (Specimen code: CASENT0009949). www.antweb.org

Doleromyrma darwiniana profile. Image: April Nobile (Specimen code: CASENT0009949). www.antweb.org

[Doleromyrma darwiniana] dorsal view. Image: April Nobile (Specimen code: CASENT0009949). www.antweb.org Image — Doleromyrma darwiniana dorsal view. Image: April Nobile (Specimen code: CASENT0009949). www.antweb.org

Biology

Shattuck (1999) notes that although frequently encountered [in Australia], Doloromyrma "has received little attention in the published literature." He continues: "They occur most commonly in dry forested areas, including coastal scrub or heath, where they nest in soil, under rocks or rotten logs, or occasionally in abandoned nests of other ants. Nests usually contain several hundred workers which disperse quickly into protected areas when disturbed." They are occasionally found in houses in both Australia (Nikitin 1979) and New Zealand (Keall 1979). Specimens of D. darwiniana in this country have been collected mainly in urban locations, industrial and residential (domestic gardens, for example).

Taylor (1959) noted numerous portions of arthropod exoskeleton in the nest referred to above. This species is clearly a generalist because he also observed a small group of workers tending root-feeding homoptera; and in the laboratory, sugar and honey were "eagerly accepted."

Appear to spread predominantly by budding and can build up large densities. Commonly found nesting in situations such as potted plants, probably facilitating their spread around New Zealand.

Pest Status

Not capable of stinging but will occasionally enter houses in large numbers foraging for sweet foods. Attains large densities in urban gardens becoming a nuisance and may displace other invertebrates. Tends aphids and mealy bugs and may also spread disease (Keall 1979). Has not been collected from native habitats.